sql统计－关于学生成绩
sql统计－关于学生成绩
学生成绩表(stuscore)：
| 姓名：name |
课程：subject |
分数：score |
学号：stuid |
| 张三 |
数学 |
89 |
1 |
| 张三 |
语文 |
80 |
1 |
| 张三 |
英语 |
70 |
1 |
| 李四 |
数学 |
90 |
2 |
| 李四 |
语文 |
70 |
2 |
| 李四 |
英语 |
80 |
2 |
创建表
问题：
1. 计算每个人的总成绩并排名(要求显示字段：姓名，总成绩)
2. 计算每个人的总成绩并排名(要求显示字段: 学号，姓名，总成绩)
3. 计算每个人单科的最高成绩(要求显示字段: 学号，姓名，课程，最高成绩)
4. 计算每个人的平均成绩（要求显示字段: 学号，姓名，平均成绩）
5. 列出各门课程成绩最好的学生(要求显示字段: 学号，姓名,科目，成绩)
6. 列出各门课程成绩最好的两位学生(要求显示字段: 学号，姓名,科目，成绩)
7. 统计如下：
| 学号 |
姓名 |
语文 |
数学 |
英语 |
总分 |
平均分 |
|
|
|
|
|
|
|
|
8．列出各门课程的平均成绩（要求显示字段：课程，平均成绩）
9．列出数学成绩的排名（要求显示字段：学号，姓名，成绩，排名）
10．列出数学成绩在2-3名的学生（要求显示字段：学号，姓名,科目，成绩）
11．求出李四的数学成绩的排名
12．统计如下：
| 课程 |
不及格（0-59）个 |
良（60-80）个 |
优（81-100）个 |
|
|
|
|
|
13．统计如下：数学:张三(50分),李四(90分),王五(90分),赵六(76分)
答案：
1. 计算每个人的总成绩并排名
select name,sum(score) as allscore from stuscore group by name order by allscore
2. 计算每个人的总成绩并排名
select distinct t1.name,t1.stuid,t2.allscore from stuscore t1,
(
select stuid,sum(score) as allscore from stuscore group by stuid
)t2
where t1.stuid=t2.stuid
order by t2.allscore desc
3. 计算每个人单科的最高成绩
select t1.stuid,t1.name,t1.subject,t1.score from stuscore t1,
(
select stuid,max(score) as maxscore from stuscore group by stuid
) t2
where t1.stuid=t2.stuid and t1.score=t2.maxscore
4.计算每个人的平均成绩
select distinct t1.stuid,t1.name,t2.avgscore from stuscore t1,
(
select stuid,avg(score) as avgscore from stuscore group by stuid
) t2
where t1.stuid=t2.stuid
5.列出各门课程成绩最好的学生
select t1.stuid,t1.name,t1.subject,t2.maxscore from stuscore t1,
(
select subject,max(score) as maxscore from stuscore group by subject
) t2
where t1.subject=t2.subject and t1.score=t2.maxscore
6.列出各门课程成绩最好的两位学生
select distinct t1.* from stuscore t1
where t1.stuid in
(select top 2 stuscore.stuid from stuscore where subject = t1.subject order by score desc)
order by t1.subject
7.学号 姓名 语文 数学 英语 总分 平均分
select stuid as 学号,name as 姓名,
sum(case when subject='语文' then score else 0 end) as 语文,
sum(case when subject='数学' then score else 0 end) as 数学,
sum(case when subject='英语' then score else 0 end) as 英语,
sum(score) as 总分,(sum(score)/count(*)) as 平均分
from stuscore
group by stuid,name
order by 总分desc
8.列出各门课程的平均成绩
select subject,avg(score) as avgscore from stuscore
group by subject
9.列出数学成绩的排名
declare @tmp table(pm int,name varchar(50),score int,stuid int)
insert into @tmp select null,name,score,stuid from stuscore where subject='数学' order by score desc
declare @id int
set @id=0;
update @tmp set @id=@id+1,pm=@id
select * from @tmp
select DENSE_RANK () OVER(order by score desc) as row,name,subject,score,stuid from stuscore where subject='数学'
order by score desc
declare @tmp table(pm int identity(1,1),name varchar(50),score int,stuid int)
insert into @tmp
select name,score,stuid from stuscore where subject='数学' order by score desc
select * from @tmp
10. 列出数学成绩在2-3名的学生
select t3.* from
(
select top 2 t2.* from (
select top 3 name,subject,score,stuid from stuscore where subject='数学'
order by score desc
) t2 order by t2.score
) t3 order by t3.score desc
11. 求出李四的数学成绩的排名
declare @tmp table(pm int,name varchar(50),score int,stuid int)
insert into @tmp select null,name,score,stuid from stuscore where subject='数学' order by score desc
declare @id int
set @id=0;
update @tmp set @id=@id+1,pm=@id
select * from @tmp where name='李四'
12. 课程 不及格（-59） 良（-80） 优（-100）
select subject,
(select count(*) from stuscore where score<60 and subject=t1.subject) as 不及格,
(select count(*) from stuscore where score between 60 and 80 and subject=t1.subject) as 良,
(select count(*) from stuscore where score >80 and subject=t1.subject) as 优
from stuscore t1 group by subject
declare @s varchar(1000)
set @s=''
select @s =@s+','+name+'('+convert(varchar(10),score)+'分)' from stuscore where subject='数学'
set @s=stuff(@s,1,1,'')
print '数学:'+@s